MySQL Connection Timeout Issue - Grails Application on Tomcat using Hibernate and ORM

Question

I have a small grails application running on Tomcat in Ubuntu on a VPS. I use MySql as my datastore and everything works fine unless I leave the application for more than ha

Answer 1

Starting from grails 2.3.6 default configuration already has options for preventing closing connection by timeout

These are the new defaults.

    properties {
       // See http://grails.org/doc/latest/guide/conf.html#dataSource for documentation
       ....
       minIdle = 5
       maxIdle = 25
       maxWait = 10000
       maxAge = 10 * 60000
       timeBetweenEvictionRunsMillis = 5000
       minEvictableIdleTimeMillis = 60000
       validationQuery = "SELECT 1"
       validationQueryTimeout = 3
       validationInterval = 15000
       testOnBorrow = true
       testWhileIdle = true
       testOnReturn = false
       jdbcInterceptors = "ConnectionState;StatementCache(max=200)"
       defaultTransactionIsolation = java.sql.Connection.TRANSACTION_READ_COMMITTED
    }

Answer 2

Add these parameters to dataSource

        testOnBorrow = true
        testWhileIdle = true
        testOnReturn = true

See this article for more information http://sacharya.com/grails-dbcp-stale-connections/

Answer 3

What does your JDBC connection string look like? You can set an autoReconneect param in your data source config, e.g.

jdbc:mysql://hostname/mydb?autoReconnect=true

Answer 4

In grails 1.3.X, you can modify the evictor values in the DataSource.groovy file to make sure pooled connections are used during idle. This will make sure the mysql server will not time out the connection.

production {
  dataSource {
    pooled = true
    // Other database parameters..
    properties {
       maxActive = 50
       maxIdle = 25
       minIdle = 5
       initialSize = 5
       minEvictableIdleTimeMillis = 1800000
       timeBetweenEvictionRunsMillis = 1800000
       maxWait = 10000
    }
}

A quick way to verify this works is to modify the MySQL my.cnf configuration file [mysql] element and add wait_time parameter with a low value.

Answer 5

Try increasing the number of open MySQL connections by putting the following in your DataSources.groovy:

dataSource {
     driverClassName = "com.mysql.jdbc.Driver"
     pooled=true
     maxActive=10
     initialSize=5
     // Remaining connection params
}

If you want to go the whole hog, try implementing a connection pool; here is a useful link on this.

Answer 6

Referring to this article, you have stale connections in your DBCP connections pool that are silently dropped by OS or firewall.

The solution is to define a validation query and do a sanity check of the connection before you actually use it in your application. In grails this is actually done by modifying the grails-app/conf/spring/Resource.groovy file and add the following:

beans = {
  dataSource(BasicDataSource) {
    //run the evictor every 30 minutes and evict any connections older than 30 minutes.
    minEvictableIdleTimeMillis=1800000
    timeBetweenEvictionRunsMillis=1800000
    numTestsPerEvictionRun=3
    //test the connection while its idle, before borrow and return it
    testOnBorrow=true
    testWhileIdle=true
    testOnReturn=true
    validationQuery="SELECT 1"
  }
}